1. Technical Field
The present invention relates to a projector and an image display system.
2. Related Art
In the past, there has been known a projector having a light source, a light modulation device for modulating the light emitted from the light source, and a projection optical device for projecting the light thus modulated on a target projection surface such as a screen. As the light modulation device used for such a projector, a transmissive or reflective liquid crystal panel or a digital micromirror device (DMD; a registered trademark of Texas Instruments in the United States) is adopted in some cases.
Incidentally, in recent years, there has been proposed an image display device forming a right-eye image and a left-eye image as parallax images, and individually inputting these images respectively to the right eye and the left eye of the observer to thereby display an image (hereinafter abbreviated as a “three-dimensional image” in some cases), which can be viewed stereoscopically due to the parallax (e.g., JP-A-2011-48071 (Document 1)).
In the projector described in Document 1, the DMD described above is adopted as the light modulation device, and a polarization plate wheel and a color wheel are disposed on the light path of the light from the light source to the DMD.
The polarization plate wheel is provided with a first polarization area, a second polarization area, and a non-polarization area. Among these areas, the first polarization area transmits a first polarization component perpendicular to the radial direction of the wheel, and blocks another polarization component (e.g., a second polarization component). Further, the second polarization area transmits the second polarization component parallel to the radial direction of the wheel, and blocks another polarization component (e.g., the first polarization component). It should be noted that the non-polarization area transmits all polarization components of the incident light.
The color wheel is provided with an R area transmitting a red component among the incident light, a G area transmitting a green component, a B area transmitting a blue component, and a W area transmitting all of the color components.
Further, in the case of displaying a two-dimensional image in the projector, the polarization plate wheel is stopped in the state in which the non-polarization area is located on the light path, the color wheel is rotated, and thus the DMD forms a color image corresponding to the colored light transmitted through the non-polarization area and the color wheel to thereby form and then project the two-dimensional image.
On the other hand, in the case of displaying a three-dimensional image, the polarization plate wheel and the color wheel are rotated in sync with each other, and thus a color image corresponding to the colored light transmitted through the polarization plate wheel and the color wheel is formed by the DMD. Thus, the red image, the green image, and the blue image constituted by the first polarization component and the red image, the green image, and the blue image constituted by the second polarization component are formed and then projected. Then, by observing the images via a pair of glasses having a filter similar to the first polarization area described above disposed at the position corresponding to either one of the right eye and the left eye, and a filter similar to the second polarization area described above disposed at the position corresponding to the other eye, the observer observes the three-dimensional image.
However, in the projector described in Document 1 mentioned above, it is required to rotate the polarization plate wheel and the color wheel in sync with each other in the case of displaying the three-dimensional image. Therefore, if the rotational phases of the wheels are shifted from each other, or the rotational speed of each of the wheel is varied, for example, there arises a problem that the three-dimensional image fails to be appropriately displayed.